Despite hundreds of years of research on the human body, a new discovery at the University of Virginia just goes to show that there are still parts of the body yet to be discovered. For the first time, researchers have discovered that the brain is directly connected to the immune system, overturning the well-established notion that no such connections existed.
The lymphatic system is a key component of the immune system. The lymphatic system is made up of lymph vessels, organs, and lymph nodes that help to create immune cells to fight disease. It also filters the lymph (colorless fluid containing white-blood cells, proteins, and fat) of any debris or harmful substances as it drains from body tissues to the bloodstream.
Image Source: PaloAlto Michelle Constantini
Researchers were able to discover lymphatic vessels in the mouse brain by using a technique that allows the entire membrane covering the brain, called the meninges, to be observed on a single microscope slide. The researchers were looking to find out how immune cells get into and out of the meninges when they started noticing a vessel pattern in the membrane. They confirmed the presence of lymphatic vessels using immunohistochemistry techniques.
The lymphatic vessels in the brain start above both eyes and move upward through the meninges, which surround the outside of the brain. Compared to the lymphatic vessels of the rest of the body, the vessels found in the meninges are narrower, cover less tissue area, and have less complex branching patterns. The researchers speculate that these vessels have previously not been identified because of how close they are to the major blood vessels of the brain, making them difficult to spot.
This research has huge implications for future research on neurological diseases, as the researchers suggest that the underlying causes of many neurological diseases may lie in malfunction in the immune system connections to the brain. For example, the researchers suggest that the buildup of toxic protein associated with Alzheimer’s disease may occur because the lymph vessels are not clearing away the protein properly. This discovery opens up a whole new line of potential research and is hopefully another step towards finding treatments and cures for some of the world’s most debilitating diseases.
Feature Image Source: Making the Connections Eduardo Mueses